U.S. Pat. No. 4,969,310 issued Nov. 13, 1990 to Hershey Lerner et al. under the title Packaging Machine and Method and assigned to the assignee of this patent (the SP Patent) discloses and claims a packaging machine which has enjoyed commercial success.
While the machine of the SP Patent has been successful, a problem has been experienced in its closure section. The problem is that too frequently due to weight of the products there is slippage of bags relative to pairs of opposed belts used to transport bags through a heat sealer. In addition, slippage of the bag fronts relative to the backs occurs resulting in poor seal quality. Alternatively or additionally it is too often necessary to provide a conveyor or other support for bags as they are transported through the sealer.